Berlin 2024 – scientific programme
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BP: Fachverband Biologische Physik
BP 20: Poster IIIa
BP 20.9: Poster
Wednesday, March 20, 2024, 11:00–14:30, Poster B
Metabolically controlled bioconvection in suspensions of photoactive microbes — •Florian Böhme1, Alexandros Fragkopoulos1,2, Nicole Drewes2, and Oliver Bäumchen1,2 — 1University of Bayreuth, Experimental Physics V, 95447 Bayreuth, Germany — 2Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany
Photosynthetic microbes have evolved and successfully adapted to environmental changes of their habitat. In the abscence of light, they can still sustain their biological functionality and metabolic activity through aerobic respiration. However, for the soil-dwelling microalga Chlamydomonas reinhardtii, their environment is often deprived of both oxygen and light, resulting in a significant reduction of their swimming velocity [1]. Here, we investigate the effect of these motility changes on the emergence of bioconvection, a collective phenomenon that arises due to the natural tedency of the bottom-heavy cells to move against gravity. We show that the motility change that is associated to the metabolic switch between photosynthesis and anaerobic respiration is sufficient to induce or prevent the formation of bioconvective plumes. Our experiments use a side-view perspective allowing us to extract the local cell density and flow fields of single bioconvection plumes, in addition to the wavelength and the spatiotemporal evolution of the pattern. In particular, we extract how these parameters depend on the single-cell motility.
[1] A.A. Fragkopoulos et al., J. R. Soc. Interface 18, 20210553 (2021).
Keywords: Microswimmers; Chlamydomonas; Bioconvection; Active suspensions; Living fluids